1. Field of the Invention
The present invention relates to a lining structure which is effective for a measure against damage of a lining member due to a difference in thermal expansion under high temperature and high pressure. The lining member is provided on a metal base material of an insertion tube for adding a chemical used for adding a chemical to a reaction vessel for leaching under high temperature and high pressure. The present application claims priority as a basis for Japanese Patent Application No. 2013-127541 filed in Japan on Jun. 18, 2013, and this application is incorporated herein by reference.
2. Description of Related Art
Conventionally, as disclosed in Patent Literature 1, there is a technique in which a lining member is provided within a tube to prevent leakage of fluid of high temperature or high pressure, or to protect the tube from corrosion, wear, contamination, or the like.
Based on such a technique, as illustrated in FIG. 3, for example, in a nickel hydrometallurgical process using a high pressure sulfuric acid leaching process, a lining member 120 is provided on a base material member 110 of an insertion tube 103 for adding a chemical used for adding an acidic chemical to an autoclave 102, and a metal lining is applied by the lining member 120.
As illustrated in FIG. 4, the base material member 110 has, for example, a cylindrical tube section 111 and a flange section 112 that protrudes outward at one end of the tube section 111, and is formed of a metal base material, such as Ti (titanium). The lining member 120 has, for example, a cylindrical tube section lining section 121 provided on an inner surface 111a of the tube section 111 of the base material member 110 and a disc-shaped flange lining section 122 provided on the flange section 112 of the base material member 110, and is formed of a lining material, such as Ta (tantalum).
The lining material of the flange lining section 122 is explosively welded to the flange section 112 of the flat base material member 110, and the flange lining section 122 is joined to the tube section lining section 121 by welding. Moreover, generally, such a conventional insertion tube 103 for adding a chemical has a structure that the tube section lining section 121 and the flange lining section 122 are joined substantially orthogonally.
The autoclave 102 is in a predetermined high temperature and high pressure state during operation. However, during periodic inspection, repair, or the like, the temperature and even the atmospheric pressure of the autoclave 102 are lowered, and the autoclave 102 is in a normal temperature and normal pressure state. Accordingly, a difference in thermal expansion occurs between the base material member 110 and the lining member 120 that normally have a difference in coefficients of thermal expansion. Moreover, it is structured that the flange lining section 122 is explosively welded to the flange section 112 of the base material member 110 and is joined to the tube section lining section 121 by welding, and that the tube section lining section 121 and the flange lining section 122 are joined substantially orthogonally. Consequently, it is structured that stress due to the difference in thermal expansion is concentrated on the flange lining section 122.
Incidentally, when the metal base material is Ti (titanium), a coefficient of thermal expansion thereof is approximately 8 to 9 μm·m−1·K−1, and when the lining material is Ta (tantalum), a coefficient of thermal expansion thereof is approximately 6 to 7 μm·m−1·K−1. The coefficient of thermal expansion of the lining member 120 is smaller than that of the base material member 110 by about 30 percent.
Therefore, when the insertion tube 103 for adding a chemical is thermally expanded under high temperature and high pressure, the lining member 120 having a smaller coefficient of thermal expansion cannot absorb the expansion of the flange section 112, and a crack occurs in the lining member 120. Accordingly, there is a possibility that the base material member 110 of the insertion tube 103 for adding a chemical and a nozzle section of the autoclave 102 are damaged.
When this is left alone, the damage is progressed to an extent that an inside and an outside of the autoclave 102 are communicated with each other. As a result, high pressure steam and a chemical are jetted out from the autoclave 102 and a situation becomes seriously dangerous. Besides that, since it is necessary to stop operation and perform replacement and repair work of various members, production efficiency is significantly reduced.